Treatment of fish skins



Patented June 1930 as on, or LONDON, nnenanp mar-m1 or men sxn'vs no Drawing, Application fled January 24, 1928, Serial No. 249,204, and in Belgium January as, 1927'.

This invention relates to an improved process for the preparatory treatment of skins of fish such as and in particular, the Plagiostomi.

5 The invention has for its object a process for the preparatory treatment of skins of fish such as, and in particular, the Plagiostomi which constitute, among the Chondropterygii-Selachii, an order to which the sharks belong the said process presenting numerous advantages, in particular that of considerably reducing the operation of tanning proper which may, if desired, be done away with altogether, considerably reducing the cost price of the leather, a further advantage of the process lying in the fact that it permits of obtaining a leather which is at the same time very supple and, very resistant.

The present invention consists of a process 2 in which the skins, after the known treatment with lime, but for a considerably reduced duration are subjectedto the action of colloids, of the type of gum tragacanth or colloids which originate from radiate parts of plants (with radiate fibrous structureg. Traganth or tragacanth is a kind of gumo tained from various of Astragalus, Fmnum Grmcum is theelongated legume of Siligna. dulcis, the alga is itself a. fiber.

As a. result of the preparatory treatment,

the operation of tanning proper can be considerably reduced; for instance, a tanning by the chrome process of from 4 to 5 hours will be sufiicient to obtain a leather of excellent 7 quality. This result may he explained by the fact that by this treatment the fibres of the skin appear to surround themselves with an insulating envelope of the colloidal substance,

in such way that a sort of action is 49 obtained, the difi'erent fibres being so insulated from one another that the fibrous congloinerate then presents a cellular structure. This treatment with colloids may be simply followed by a mechanical treatment consisting in the skins to alternate tension and expansion by which the fibres so insuiated will be disposed parallel to one another, and the leather obtained present an extraordinary suppleness and also very This preparatory treatment with colloidsmay, moreover, be combined with the treatment for hating the skins by enzymes, to. which the treatment with colloids will be consecutive, after which the skins will be tanned or simply subjected to a mechanical treatment.

By way of an example of carrying the process into effect, the operation may be as follows: Gum tragacanth or water of algae or of fenugreek are diluted in such way as to form a viscous liquid of about 5% concentration in which the limed skins are treated for approximately 6 hours at a temperature of about 30 (1, in a pit where they are stirred or in a fulling mill. After a five-minute rinsing, the skins are dried and treated mechanically as explained above or, again, subjected to a tanning by a vegetable or mineral process, for instance, to a tanning by chrome.

The skins of Plagiostomi prepared in accordance with the process with colloids, may, moreover, be employed to advantage for the production of waterproof leathers, and for this purpose the skins so treated are dried and impregnated with a waterproofing solution such as, for preference, a solution of rubber in benzols or a solution of stearate of lime in benzols; after drying, the skins are subjected to a currying process. so

It is naturally understood that it is possible, without departing from the invention, to make variations and modifications of details i]; the process which forms the subject therc- 8 o Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. A process for the preparatory treatment of skins of Plagiostomi and the like, including the steps of treating the skins with lime and then for a considerably reduced period .1 subjecting them to the action of colloids of the type of gum tragacanth. 2. A process for the preparatory treatment of skins of fish as claimed in claim 1 including-the additional steps ofbatin the skins with enzymes after limin and fore colloidal treatment, the said shins,

after a. short proximately 6 hours at a treatment with lime being subjected to the enzymic action of enzymes prior to the treatment with colloids.

3. A process as claimed in claim 1 wherein the skins are waterproofed by impregnating them after drying with a benzolic solution of waterproofing material.

4. A process for the treatment of skins of sharks and the like, comprising the introduction of said skins after liming and other preparatory treatment into a "viscous liquid containing about 5% of um tragacanth or water extract of algae or o fenugreek for aptemperature of about 30 0., sprinkling said skins, and drying said skins to prepare them for final treatment.

In testimony whereof I afiix my signature. ALFRED EHRENREICH. 

